This invention relates generally to pnuematic deicers of the type having a deformable sheet secured with respect to the leading edge of an aircraft wing, the deicer also having spaced, parallel, inextensible threads to define a series of inflatable sections in the deicer and which may be alternately expanded and contracted by fluid pressure to break up ice accumulations which undesirably tend to form on the surface of the deicer when the aircraft is operating in severe climatic conditions.
During flight, aircraft are periodically exposed to conditions of precipitation and low temperatures which may cause the formation of ice on the leading edges of their wings, the airfoils. During such conditions, it is imperative that this ice be removed if the aircraft is to perform safely. To this end, various types of structures have been designed and utilized to break up and remove such ice in order to insure the safe performance of aircraft. However, icing conditions normally constitute only a relatively small portion of the total flight time for most aircraft. During ice-free periods, when the deicing equipment is not in operation, it is important to maintain the exterior surfaces of the deicers smooth because these surfaces must serve as the airfoils in providing for the safe flight of the aircraft. Any irregularity on these surfaces can seriously hinder the safe performance of the aircraft by creating dangerous air turbulance. Further, excessive bulk and weight of the deicer would increase the cost of materials unnecessarily, the manufacturing cost and also the weight of the aircraft, resulting in unnecessary fuel consumption.
Prior to the present invention, various efforts have been made in the design and manufacture of pneumatic deicing equipment with varing degrees of commercial success and reliability. One of the earlier attempts to solve the problem of deicing is described in U.S. Pat. No. 2,168,328 to Diehl. The Diehl disclosure is particularly concerned with more positively holding the deicer sheet against the leading edge of the aircraft to avoid its flapping. The disclosure is directed to equalizing the pressure on the under surface of the deicer with the pressure on its outer surface. To that end, the Diehl deicer utilized a resilient, elastomeric member molded in a complex design requiring sophisticated fabrication techniques at obviously excessive costs in terms of materials, molds and the like and requiring highly skilled technicians.
Eventually, pnuematic deicers turned to the use of a plurality of layers of sheet material to effect the desired ice removing function. Examples of these designs are found in U.S. Pat. No. 2,440,533 to Antonson and U.S. Pat. No. 2,957,662 to Hess. According to those disclosures, air chambers were formed in the airfoil by a large number of layers of elastomeric sheets, sewn or otherwise joined, in intricate patterns which of necessity undesirably increased the amount of materials, weight, manufacturing time and cost. Although such designs overcame the need for molded parts, they did include the use of materials with complex cross-sectional configurations, probably extruded, which still precluded the utilization of more standardized sheeting material with rectangular cross-sections.
A yet further improvement over the above-mentioned prior art approaches to a more economical and reliable solution to the deicing problem is described in U.S. Pat. No. 3,604,666 to Achberger. According to that disclosure, separate tubes of resilient, elastomeric material were spaced in a parallel array between interior and exterior sheeting members. Although reliable performance resulted, and molding and extrusion were eliminated, the separate tubes had to be individually attached to the adjacent layers in a precise orientation. This required a high degree of craftsmanship for accurate fabrication along with the high cost and unnecessary weight which resulted from the use of the excess materials of the separate tubes.
Perhaps the most desirable pnuematic deicers in the prior art are described in U.S. Pat. No. 3,370,814 to Kageorge, et al. and in U.S. Pat. No. 3,690,601 to Roemke. According to those disclosures, simple elastomeric sheeting material with rectangular cross-sectional configurations was employed without the utilization of excess material to constitute the passages which functioned as the prior art pnuematic tubes. No intricate extrusion or molding of the deicer material was needed, and the amount of material in terms of cost, weight and manufacturing precision was minimized when compared with the prior art available as of that time. The deicer passages were formed by stitching together superposed layers of resilient, elastomeric sheeting. The stitches corresponded to the edges of the passages for constraining the movement of fluid which effected the predetermined expansion and contraction of the deicer to break and remove the ice on the airfoil and thereby maintain the aircraft in a safe mode of operation.
The present invention is directed to pnuematic deicers which overcome the problems of the prior art. They are constructed with discrete passages for air or other fluid whereby the passages may be rapidly and reliably inflated and deflated to expand and contract the deicer for the removal of ice formations from the leading edge of aircraft wings. These deicers are constructed from a minimum amount of resilient, elastomeric sheeting material and with rectangular cross-sectional configurations for reduced cost and weight. They can be assembled without the employment of highly skilled technicians. Further, increased efficiencies are realized by aircraft on which they are employed because of their reduced weight as well as their smooth conformance to the preferred airfoil shape when such deicers are not in operation.
The foregoing has outlined some of the pertinent objects and advantages of the present invention. These objects and advantages should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and advantages as well as a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiments in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.